In November 2000, California voters approved the Substance Abuse and Crime Prevention Act of 2000 (Proposition 36), which mandates diversion of drug-abusing offenders to community-based treatment programs in lieu of incarceration. Building on current research efforts at the state, county, and treatment provider levels, the applicants propose to conduct two separate but interrelated studies to examine the treatment system impact and outcomes of Proposition 36 in five selected counties. Using both qualitative and quantitative methods, the System Impact Study will explore the effects of the implementation of Proposition 36 on California's treatment service delivery system (counties and providers), the system's response, and the relationships between the treatment system and the criminal justice system. The Treatment Outcome Study will assess treatment outcomes among Proposition 36 patients as influenced by program/service characteristics and by patient characteristics within the broad environmental context of the five counties' service delivery systems. Findings from the proposed work will elucidate the effects of implementing this new drug policy on the treatment service delivery system and will identify factors that influence the treatment outcomes among California's large drug-abusing offender population. The project will produce recommendations to improve treatment strategies and inform future policy and practice at the national, state, and local levels.